Window covering mainly is installed on a window to block sunshine and provides an ornamental function. To meet varying use requirements of consumers, myriad types of window coverings have been introduced on the market, such as Roman shades, Venetian blinds and the like. Control methods of Roman shades can be divided into one with cords to control retraction and extension and another one disclosed in U.S. Pat. No. 5,813,447 shown in FIGS. 1 and 2. Refer to FIGS. 1 and 2, the Cellular shade 1 mainly includes an upper rail 11 holding an automatic winding means 12 inside and a fabric shade 2 located at the bottom thereof, and the fabric shade 2 has two corresponding bracing blades 21 at two sides. Each bracing blade 21 has a plurality of apertures 22 latched with the fabric shade 2. The fabric shade 2 has a bottom end fastened to a lower rail 3 at the lowest side.
The automatic winding means 12 held in the upper rail 11 consists of a great number of elements, is difficult to fabricate and occupies a great deal of space. As a result, it needs a thicker shaft 121 and requires a greater internal space of the upper rail 11 for holding the great number of elements while winding the Cellular shade 1. The apertures 22 on the bracing blades 21 aim to latch with the fabric shade 2 to facilitate balance of retraction or extension of the fabric shade 2 at two sides. When a user grips the lower rail 3 to move upwards or pull downwards incorporating with the automatic winding means 12, the fabric shade 2 is wound or extended. It is a troublesome operation. There is still room for improvement in terms of usability.